Lubricating oil composition

ABSTRACT

LUBRICATING OIL COMPOSITIONS EXHIBITING GOOD VISCOSITY INDEX, POUR POINT, RESISTANCE TO OXIDATION, AND SHEAR STABILITY PROPERTIES MAY BE FORMULATED FROM MINERAL OIL OR SYNTHETIC OIL BASE STOCKS AND OILY ETHYLENE-PROPYLENE COPOYLYMERS BOILING ABOUVE 450* C. PREPARED FROM ETHYLENE AND PROPYLENE IN MOLE RATIO OF 1.5-0.43:1.

Jan. 11, 1972 Filed Nov. 15, 1968 R. DUPAS ET AL LUBRICATING OILCOMPOSITION 2 Sheets-Sheet l wr LUMPULYMEI? 1w, 798. 9C 7378.

20 FIG. 4

/o WT EUMPULYMEI? United States Patent 3,634,249 LUBRICATING OILCOMPOSITION Robert Dupas and Marcel Ostyn, Mont-Saint-Aignan, France,assignors to Esso Research and Engineering Company Filed Nov. 15, 1968,Ser. No. 776,012 Claims priority, application France, Nov. 20, 1967,

Int. or. (from 1/18 US. Cl. 252-59 7 Claims ABSTRACT OF THE DISCLOSURELubricating oil compositions exhibiting good viscosity index, pourpoint, resistance to oxidation, and shear stability properties may beformulated from mineral oil or synthetic oil base stocks and oilyethylene-propylene copolymers boiling above 450 C. prepared fromethylene and propylene in mole ratio of 1.5-0.4321.

The present invention relates to compositions of oily ethylene/propylenecopolymers and mineral and/or synthetic oils of the ester type. Thesecompositions have good properties as regards viscosity, in particularviscosity index, pour point, stability in respect of shearing,oxidation, heat etc. It is possible to obtain multi-grade oils rising tograde SAE IO-W-SO.

It is well known that to obtain multi-grade lubricating oils of highviscosity index and low pour point, it is possible to use threeprincipal methods:

The first consists of intensifying the refining of the mineral oils; butin this case, oils of high viscosity index can only be obtained if theviscosity remains low; it is thus possible to obtain the grade SAE-W-20, but if a change be made to gnade SAE 30, one 'is confined to theoils SAE 20-W-30.

According to the second method, recourse is had to synthetic oils, butaccording to current techniques, with oils obtained from olefins, it isnot possible to attain the grades W40 or 10-W-50 and with ester-typeoils one is confined to 5-W-20 and l0-W-20.

Finally, the attempt can be made to use additives for improving theviscosity index and the pour point of mineral or synthetic-based oils.

The additives at present used for the purpose are, generally speaking,polymers or copolymers of high molecular weight. They fail to give fullsatisfaction because they stand up badly to oxidation and shearingforces, especially those which appear in the systems of geartransmission or in piston pumps for hydraulic circuits. Now, technicaldevelopment in these fields takes the form of ever more severemechanical stresses. Indeed, we are at present faced with two kinds ofadditive improving the viscosity index: on the one hand those which areof the polyisobutylene type whose shearing strength is acceptable, asthey yield in the sonic breakdown test viscosity gradients in the regionof 24% for a 10% solution in a mineral-oil, but they deteriorate throughoxidation and moreover those which, being of the polymethacrylate type,fumarate etc., are more resistant to oxidation, but do not withstandshearing, the drop in viscosity in the sonic breakdown test being in theregion of 50% Furthermore, the present additives improving the viscosityindex greatly increase the viscosity of the oils at low temperature, sothat there is a considerable discrepancy at 17.8 C. between the measuredviscosity and the viscosity extrapolated by means of the ASTMviscosity-temperature chart.

It is known that it is possible to prepare oils by the copolymerisationof ethylene and propylene, whose molar ratio is between 1.5 and 0.43 inthe presence of catalysts ice consisting of organo-metallic compounds ororganic compounds of metals. The catalysts which may be used areselected from mixtures of a heavy metal compound se lected fromSubgroups B of Groups IV to VII or Group VIII of the Periodic Table, andone of the following:

(a) An organic compound of a metal of Groups I to IV, preferably GroupII or III, of the Periodic Table. (b) A metal hydride or organometallichydride. (c) A halogenated organo-metallic compound. Preferably thecatalyst comprises tri-alkyl aluminum and titanium tetrachloride, themolar ratio TiCl /R Al (R=a1kyl) being between 1:1 and 10:1 preferablyabout 3:1. The catalyst may if desired be prepared in situ, in a solventcomprising a saturated hydrocarbon e.g. heptane and/or an aromatichydrocarbon e.g. xylene and in a quantity such that the ratio by weight:

solvent total dissolved polymer is between 10/7 and 1/ 3.Copolymerisation is carried out in an inert atmosphere, at atmosphericor higher pressure, at a temperature between 40 C. and +80 C. and forpreference from -10 C. and +20 C. After decomposition and elimination ofthe catalytic complex, the polymer is filtered and the solventevaporated. Hydrogenation on nickel may be carried out under the usualconditions.

Distillation under vacuum (pressure lower than 1 mm. Hg) makes itpossible to collect inter alia the fraction distilling above 450 C.(boiling point converted to that at normal pressure). The mean molecularweight of the fraction distilling above 450 C. thus obtained is in theregion of 1000 to 3000.

The applicants have discovered that these products, when added tomineral and/or synthetic oils of the ester type, make it possible toprepare excellent compositions, characterized by among other properties,their qualities of viscosity, their pour points, their resistance tooxidation and heat, their total shearing strength etc.

These compositions may contain from 1 to 70% by weight of oilyethylene-propylene copolymer.

These synthetic oils of the ester type may for preference bedi-2-ethyl-hexyl, di-decyl, or di-nonyl adipate or sebacate, as well asthe esters of pentaerythritol.

The following examples which are given by way of illustration and in noway restrictively will better show the scope and importance of theinvention:

EXAMPLE 1 (l) A mineral base oil A and the heavy fraction of anethylene-propylene copolymer as defined above were used. They had thefollowing characteristics.

(2) The following compositions were prepared: C 97% oil A and 3%copolymer.

C oil A and 25% copolymer. C 60% oil A and 40% copolymer.

C1 C2 Cs Viscosity at 37.8 0., est 37. 50 114. 4 235 V1scos1ty at 98.90., est 6. 11 14. 33 25. 89 Viscosity index 119 126 126 Pour point, C 12-12 -15 Flash point open vessel, C 228 228 235 They make it possible toplot the vicosity curves 37.8 C. and n98.9" C. as well as the viscosityindices (V.I.) as a function of the percentage of copolymer; thesecurves (FIG. 1) show that the improvement in the viscosity index isobtained very quickly, and is very largely constant from copolymeronwards; thickening effect is more progressive. Curve 1 is that of the 137.8 C. as a function of the percentage of copolymer.

Curve 2 is that of the viscosity of 1 98.9" C. as a function of thepercentage of copolymer, curve 3 is that of the V1. as a function of thecopolymer.

(3) The composition C which represents a motor oil SAE -W-40, wassubjected to tests making it possible to appreciate the shearingstability.

(a) Stability determined by the test termed sonic breakdown test Thisconsists of subjecting the oil to shearing forces created by a 10 kcs.oscillator at 200 watts and 98.9 C. for a determined period:

The result is expressed by:

1 being the viscosity at 98.9 C. before the test. 77 being the viscosityat 980 C. after the test.

By way of comparison, the behaviour of the same oil A was examined witha commercial additive (add.) consisting of a polymethacrylate of highmolecular Weight, the quantity of additive added representing 5.6% byweight of the oil being that which made it possible to obtainviscosities and a viscosity index comparable with those of composition CThe following results were obtained:

02 Oil A plus add.

Length of test, minutes 60 25 60 Percent drop of viscosity 0.04 0.44 1522 (b) Mechanical shearing stability (c) Stability in the test with aPeugeot 204 vehicle This test consists of subjecting the oil to themechanical shear found in the gears of the gear box and the differentialof a Peugeot 204 vehicle, type XK. The engine is mounted on the benchand the test lasts 50 hours.

By way of comparison, use was also made of oil A with 5.6% of theadditive previously specified.

The curves of FIGS. 2 and 3 show, as a function of the length ofoperation, in hours, for the composition C and for oil A with thecommercial additive, on the one hand the variations in the viscosityindex (V.I.) and on the other the variations of Afl/flo:

fl viscosity at time tviscosity at initial time. no viscosity at initaltime.

the viscosities being measured at 98.9 C.

EXAMPLE 2 With the copolymer mentioned in Example 1 and with a base oilB the following oils were prepared:

B containing 15% copolymer. B containing 32% copolymer. B containingcopolymer.

by weight in relation to the base oil B. The following results wereobtained:

B B1 132 B Viscosity at 378 0., cst 8. 25 18. 84 50. 81 74. Viscosity at98.9 (3., c 2. O6 4. 2 8. 5 11.2 Viscosity index 29 137 133 Pour point,C 42 -57 54 ---51 Flash point open vessel, C 142 156 158 160 EXAMPLE 3To ascertain the resistance to oxidation and t0 the heat of thecopolymer corresponding to the invention a product was taken of meanmolecular weight 1500, and it was subjected to differential thermalanalysis under an atmosphere of nitrogen and an oxidising atmosphere. Byway of comparison, the same test was carried out on a commercialadditive consisting of a polyisobutylene of mean molecular weight 1000.

The measurements were carried out with a commercial apparatus with alinear heating system of 1 C. per minute, and a silicone oil asreference substance.

The thermal stability is characterised by the temperature from which theproduct placed under an atmosphere of nitrogen gives a thermal effect.It manifests itself with polyisobutylene from 285 C. whereas with thepolymer corresponding to the invention it only appears at 345 C., or again in thermal stability of 60 C.

In an oxidising atmosphere, for the two products compared, theresistance to oxidation amounts to 135 and 315 C. or a gain of 180 C. infavour of the copolymer corresponding to the invention.

EXAMPLE 4 Viscosity at 98.9 C. 378 0. Measured Extrapolated Theeffective viscosity of the oil H1 at 17.8 C., very difierent from thatfurnished by extrapolation, is three times the viscosity of the oil H2.

EXAMPLE 5 A synthetic oil was taken consisting of bis 2- ethylhexyladipate and the copolymer mentioned in Example 1, according to variableproportions.

The following results were obtained:

Percent weight of oil 66 9 5 Percent weight of copolymer 33: l 8

Viscosity at 17.8 0., extrapolated, est 1 5'0 0 Viscosity at 37.8 C.,est 0 1.18 8 18 Vlscoslty at 08.0" 0., cst 11. 40 14. 20 2' 30 iscosityindex 145+ I42 112; liour point, C 54 54 -60 (,rade SAE 10-W-30 10-W-40This clearly shows the improvement in the viscosity index; the obtainingof the grades SAE 1=0-W-30 and 10-W-40 is possible.

EXAMPLE 6 6 carried out with the apparatus model CCSl sold by the firmof Cannon Instrument Co., Philadelphia, USA.

The following results were obtained:

5 D D] Dz D A synthetic oil was taken consisting of bis-Z-ethyl-hexylsebacate; to it was added the copolymer referred to in :2 g g aggggjjji3 3 j3 P 1;, -39 -45 Example 1. The following results were obtained.ggggg i Percent Weight of oil 77. 5 68. 5 65.5 10 Percent weight ofcopolymer 22.5 51.5 34.5 The exceptionally low pour points of theternary IIllX- Viscosity at -17.s 0., extrapolated, est-.. 1, 300 1, 9002, s00 W111 be noted- Viscosity at 375 0., est 61.6 90.2 107.2 EXAMPLE 8Viscosity at 988 0., cst 11.5 16.0 18. 0 u VISQOSIW Index 149 146 143 It1s likewlse possible to prepare 011s for gear boxes and Four point, C 57-54 -54 Flash oint open vessel, 235 236 236 rear axles having aviscosity which varies but little as a Grade SAE function of thetemperature, such as mixtures E and E consisting of a mineral oil G,type 150 neutral, and co- By way of compar son, the same 011 was m1xedw1th Bright polymer, according to the f ll i percentages; Stock solvent,WhlCh is the mmeral 011 having the best viscosity index in relation toits viscosity. G E! E2 The following results are obtained:

Mineral oil G 100 50 33 Oopolymer 0 5 67 25332? W522i 3 51;551:5512" 3626 solvent 100 64 74 These mixtures have the following characteristics:Viscosity at37.8 0., est 12. 61 524 90.7 139.6 Viscosity at 98.9 0., cst3. 32 32. 3 11.65 15.1 G E1 E2 Viscosity index 154 98 121 114 Pourpoint, 0-... 6O 12 21 18 Viscosity at 989 C., cst 5. 37 25.0 50 GradeSAE 5 W 20-W-30 SAE Viscosity at 17.8 C. (extrapolated), 0st 21.000iscosity iglgeg. 10g 1g 1%(2) r in The thickening by the viscous o1ltherefore causes a 3 G 1 'gdei AE 250 rapid drop in the viscosity indexof the composition and, in the best case, it is definitely only possibleto obtain grade Th present i ti h b d rib d b :way of SAE 20-W-30.explanation and in no sense restrictively. Any useful m0- A determmationwas made of the shearing stability difications may be made to it withoutdeparting from its of the composition containing 69% oil and 31% copoly-35 scope. me r, 1n a Rosch injector type KB SA 53/1 under very What isclaimed is: stringent conditions: 1. A lubricating compositioncomprising a major Temperature of oil 0 amount of a base oil1 whichidoes not mic; Ehe visiosity re- Injector inlet pressure 250 atmospheres40 'i f g a i t1 i e Se p Injector outlet pressure 1 atmosphere.conS1?tmg o 01 a Syn e 10 es er u mg 011 and a viscosity 'lIIlPIOVlHgamount of at least 1 wt. cycles per hour percent and suflicient tolmpart the v1scos1ty requirements The following results were obtalned:of a multi grade oil to the base oil of an oily copolymer Length of testin hours 0 5 10 20 40 50 Viscosity of oil at:

37.8 0., est 92.80 92.72 92.52 92. 47 92. 41 92. 34 92.07 9s. 9 0.,est--- 15.82 15.81 15.69 15.66 15.64 15.61 15.57 Viscos1ty index 145 145145 144 144 144 144 Acid number 0.26 0.26 0.26 0.20 0.26 0.20 0.29 Gradeof oil SAE 10-w-40 10-W-40 10-W-40 10-W-40 10-W-40 10-W-40 10-W-40 Thecompositions bis-2-ethyl-hexyl sebacate copolymer liquid fractionboiling above 450 C. (at normal presaccordlng to the mvention thereforeposses perfect shearsure) and having a mean molecular weight of about1000 mg Strength to 3000 obtained from the copolymerization of ethyleneAs regards resistance to oxidation, this is the outcome, 5 and propyleneusing a molar feed ratio of between 1.5- on the one hand of the wellknown stability of base oils 0.43:1 respectively, in an inert atmosphereat a temperaof ester type and the stability of the copolymer shown byture of between -40 C. and +80 C., in the presence of Example 4. acatalyst comprising a mixture of tri-allkyl aluminum and titaniumtetrachloride in a mole ratio of between 1:l EXAMPLE 7 60 and 10mTernary mixtures were taken consisting of bis-2-e hyl- 2. A compositionas claimed in claim wherein the cataheXyl p a mineral Oil D of yp 100neutral Solvent lyst is prepared in situ in a solvent selected from thegroup and the copolymer shown in Example 1, according to the consistingof a saturated hydrocarbon and an aromatic following percentages byweight: hydrocarbon so that the ratio by weight of solvent to totaldissolved copolymer is 1.43-0.33z1. D D2 D3 3. A composition as claimedin claim 1 wherein the co- Bis-2-ethyl-hexyl 0 5 15 25 polymerisation iscarried out at a temperature of between Mineral oilD 1 75 5 55 10 C and+20 C Copolymer 0 2 2O 20 4. A compositlon as cla1med 1n cla1m 1 WhlChcontains A measurement was made of the viscosity at 17.8 C. 1 to 70weight percent of the copolymer fraction. in the cold crankingsimulator; this method is shortly to 5. A composition as claimed inclaim 1 wherein the to become an ASTM method under the designationsynthetic ester lubricating oil is selected from the group DXXXX-67T; itprovides a laboratory process for deterconsisting of di-Z-ethyl hexyladipate, di-decyl adipate, diming the apparent viscosity of an engineoil at l7.8 C. nonyl adipate, di-2-ethyl hexyl sebacate, di-decylsebacate with a high proportion of shear. The measurements were anddi-nonyl sebacate.

References Cited UNITED STATES PATENTS 2,190,918 2/1940 Goethel et a1252-59 2,327,705 8/1943 Frolich et al. 25259 2,889,314 6/1959 Fritz260683.15

8 3,057,801 10/1962 Wilgus 252-59 3,389,087 6/1968 Kresge et al. 252--593,474,157 10/1969 White et a1 260683.15

5 DANIEL E. WYMAN, Primary Examiner W. H. CANNON, Assistant ExaminerU.S. Cl. X.R. 260683.15 D

